First-principles calculation of the Gilbert damping parameter via the linear response formalism with application to magnetic transition metals and alloys

A method for the calculations of the Gilbert damping parameter alpha is presented, which, based on the linear response formalism, has been implemented within the fully relativistic Korringa-Kohn-Rostoker band structure method in combination with the coherent potential approximation alloy theory. To account for thermal displacements of atoms as a scattering mechanism, an alloy-analogy model is introduced. This allows the determination of alpha for various types of materials, such as elemental magnetic systems and ordered magnetic compounds at finite temperature, as well as for disordered magnetic alloys at T = 0 K and above. The effects of spin-orbit coupling, chemical-and temperature-induced structural disorder, are analyzed. Calculations have been performed for the 3d transition metals bcc Fe, hcp Co, and fcc Ni; their binary alloys bcc Fe1-xCox, fcc Ni1-x Fe-x, fcc Ni1-x Co-x and bcc Fe1-x V-x; and for 5d impurities in transition-metal alloys. All results are in satisfying agreement with experiment.